Internal combustion engines typically contain one or more pistons. The pistons reciprocate up and down in corresponding and complementarily shaped cylinders present within the internal combustion engines. Such engines are often Otto cycle engines which employ a spark plug or the like for ignition, or Diesel cycle engines which rely on compression ignition. After ignition, which may occur on either side of a top dead center (TDC) position, the piston descends within the cylinder in a power stroke before ascending for exhaust and then back down for intake in a repeating sequence.
The pistons of such engines typically include a cylindrical base that has a bottom portion connected to a crank shaft by a connecting rod or the like, and a top portion or piston crown opposite the bottom portion. The piston crown cooperates with the cylinder head to define a combustion chamber. It is within the combustion chamber that the air and fuel are mixed and ignited.
The piston crown is typically bowl-shaped and defined by a circumferential wall that extends from the cylindrical base of the piston. The circumferential wall of the piston may also be known as the piston bowl wall. A fuel injector is typically mounted in the cylinder head and extended into the combustion chamber to communicate fuel to the combustion chamber prior to ignition. As the piston arises within the cylinder toward a (TDC) position, a small volume of air and fuel for premixed engines, air only for diesel engines (diesel engines typically include external or internal recirculated exhaust gas (EGR) but could be air only), known as squish flow is squeezed out from between the piston crown and cylinder head and into the combustion chamber. Air can also include (EGR) that is inducted with the air on the intake stroke or trapped in the cylinder from the previous engine cycle.
A problem associated with squish flow is that it follows the path of least resistance and current engine designs may not use it optimally. More specifically, as the squish flow follows the path of least resistance, it does not actually mix with flame plumes in the combustion chamber and there may be an incomplete mixing of air and fuel. Consequently, a significant amount of unburned gas may be present in the combustion chamber, thereby not allowing for beneficial mixing of air and fuel, and ultimately making for a less efficient engine, and potentially increasing the amount of soot or other pollutants produced.
Various engine configurations exist to purportedly improve fuel and air mixing prior to, or during combustion. However, such configurations face the common challenge that the piston bowl is a fixed structure that does not capitalize on squish flow and thus may not ensure optimal mixing of air and fuel within the combustion chamber. For example, U.S. Patent Application No. 2015/0260081 entitled “Turbo Vortex Piston,” discloses a piston for use in a four cycle reciprocating internal combustion engines. However, such a system does not have the capacity to reroute squish flowing away from the piston bowl back into the piston bowl to interact with the flame plumes flowing within the piston bowl. As a result, such systems do not effectively utilize squish flow to improve combustion and reduce soot emissions.
In view of the foregoing disadvantages associated with the mixture of air and fuel within engines, a need exits for a solution which provides for more interaction between the air and fuel to promote soot oxidation within the internal combustion engine. The present disclosure is directed at addressing one or more of the deficiencies and disadvantages set forth above. However, it should be appreciated that the solution of any particular problem is not a limitation on the scope of this disclosure or of the attached claims except to the extent expressly noted.